The present invention relates generally to polymer compositions and processes for their preparation, and in particular to nitrogenous polymer compositions which are useful as dye complexing agents, and to processes for their preparation.
Manufacturers of detergents and other compositions useful in laundering dyed textiles have long sought ways to address the problem of dye transfer from one article to another. One solution which has become particularly popular is to include a polymer that interacts with dyes in solution and thus reduces or eliminates the transfer of dyes from one article to another. The largest class of polymers useful as dye transfer inhibition (DTI) agents includes nitrogen-containing polymers such as poly(vinylpyrrolidone), poly(vinylimidazole), and poly(vinylpyridine)-based polymers such as poly(vinylpyridin-N-oxide) and quaternary salt forms of polyvinylpyridine polymers. As examples, U.S. Pat. No. 5,627,151 describes the use of certain copolymers including 1-vinylpyrrolidone or 1-vinylimidazole or mixtures thereof with certain other nitrogen-containing, basic ethylenically unsaturated monomers, as detergent additives. U.S. Pat. No. 5,710,119 describes the use of a copolymer of N-vinylimidazole and N-vinylpyrrolidone in a detergent composition, and U.S. Pat. No. 5,929,175 describes the use of certain water soluble poly(vinylpyridine betaines) containing a quaternary nitrogen and a carboxylate salt, as dye complexing polymers.
For most applications, the color of polymeric DTI agents is of particular importance. Highly colored materials are generally undesirable, and there is a demand in industry for low-colored polymeric Dn agents. However, the processes by which polymeric DTI agents are prepared can often impart substantial dark color to the polymers. While some of this color may be eliminated by bleaching or similar measures, such measures both present a risk to damaging the desired polymers and increase the cost of the overall manufacturing process. Particularly in the case of forming quaternary salt polymers by quaternization of a corresponding free base nitrogenous polymer, the quaternization step is known to impart significant color to the final product.
Another issue that arises in the area of DTI agents is the action of the agents to actively promote dye loss from dyed fabrics. Thus, some efforts have been made to derive copolymers which have a moderated tendency to attack and cause undesired dye loss from fabrics.
In view of this background, there remain needs for new polymer compositions useful as DTI agents, and for processes for preparing them. Desirably, processes for preparing DTI polymers would be relatively facile to conduct while providing end products of good color. Also, DTI polymer compositions having a relatively high ability to inhibit dye transfer and a relatively low tendency to cause dye loss are desired. The present invention addresses these needs.
Accordingly, in one preferred aspect, the present invention provides a process for preparing a polyvinylpyridine quaternary polymer, the process comprising polymerizing a vinylpyridine monomer in the presence of an azo initiator, to form a polyvinylpyridine polymer having a weight average molecular weight of about 2,000 to about 1,000,000. The process also includes the step of quatermizing said vinylpyridine polymer so as to form a polyvinylpyridine quaternary polymer. Inventive detergent compositions and methods of their use are provided, which include polymers so prepared functioning as dye transfer inhibition agents.
In another preferred embodiment, the invention provides a polymer composition, comprising a water-soluble polyvinylpyridine polymer, the polymer having at least one terminal group having the formula 
wherein R2 and R3 are, independently, alkyl with 1 to 3 carbons or cyano, and R4 is a group of the formula 
wherein R5 and R6 are H or alkyl and can together form a ring, R1 is an organic radical having up to about 20 carbon atoms, and R7 is H or R1 as defined above, and o and p are 0 or 1, or of the formula: 
wherein n is an integer from 0 to 5, Y is OH or a group of the formula: 
wherein q is 0 or 1, R8 and R9 are H, alkyl or hydroxyalkyl, and R1 is as defined above.
Another preferred embodiment of the present invention provides a water-soluble polyvinylpyridine quaternary polymer obtainable by a process comprising polymerizing a vinylpyridine monomer in the presence of an azo initiator to form a vinylpyridine polymer, and quaternizing the vinylpyridine polymer.
A still further preferred embodiment of the invention provides a polymer composition that includes a mixture of a first polymeric amine dye transfer agent and a second polymeric amine dye transfer agent. Particularly preferred are compositions wherein the first polymeric amine dye transfer agent is a polyvinylpyridine N-oxide polymer.
Yet other embodiments of the present invention provide detergent compositions including polymer compositions of the invention, and methods for washing dyed textiles which comprise contacting the textiles with a detergent composition of the invention.
Additional embodiments, as well as features and advantages of the invention, will be apparent from the descriptions herein.